Demo Validating Backup

In this guide, we'll walk through manually backing up your Jenkins home directory and validating the archive in an isolated environment. This process helps ensure you can fully restore Jenkins configuration, jobs, plugins, and credentials in the event of a failure.

1. Locate the Jenkins Home Directory

List the contents of /var/lib and filter for “jenkins” to identify the home directory and any existing backups:

root@host:/var/lib# ls | grep -i jenkins
drwxr-xr-x 28 jenkins jenkins    12288 Feb  7 07:05 jenkins/
-rw-r--r--  1 root    root 2209944892 Feb  3 09:00 jenkins-EOF.tar.gz
drwxr-xr-x 10 jenkins jenkins     4096 Feb  3 08:59 jenkins.bak/

You should see:

• jenkins/ – the active Jenkins home directory.
• Any previous archives like jenkins-EOF.tar.gz.

The default Jenkins home path is /var/lib/jenkins.

2. Create a Compressed Backup

Use tar to archive and compress the entire Jenkins home directory, saving it under /tmp with a timestamped filename:

root@host:/var/lib# tar -zcvf \
  /tmp/jenkins_home-$(date +"%Y%m%d%H%M").tar.gz \
  jenkins

This command will:

• Recursively package jenkins/.
• Compress the archive (.tar.gz).
• Name it with the current date and time (e.g., 202502070714).

Depending on the data size, this may take a few minutes.

3. Verify the Backup Archive

After the tar command completes, confirm the archive exists and check its size:

root@host:/var/lib# ls -lh /tmp/jenkins_home-*.tar.gz
-rw-r--r-- 1 root root 2.0G Feb  7 07:17 /tmp/jenkins_home-202502070714.tar.gz

A few gigabytes is common for Jenkins installations with extensive job history and plugins.

4. Prepare a Test Environment

To validate the integrity of your backup without impacting production, create a sandbox copy:

1. Stop the Jenkins service to avoid data changes during copy.
2. Copy the home directory to /tmp/jenkins-backup.
3. Inspect the backup contents.

4.1 Stop Jenkins

root@host:/var/lib# systemctl stop jenkins

4.2 Extract or Copy

root@host:/var/lib# cp -r jenkins /tmp/jenkins-backup
root@host:/var/lib# cd /tmp/jenkins-backup
root@host:/tmp/jenkins-backup# ls
config.xml    jobs/       plugins/    secrets/    users/
queue.xml     scriptApproval.xml  tools/    updates/    workspace/

Common subdirectories in a Jenkins home backup:

5. Point a Jenkins Instance at the Backup

Launch a standalone Jenkins instance using your sandboxed backup directory as JENKINS_HOME:

1. Export the environment variable:

   root@host:/tmp/jenkins-backup# export JENKINS_HOME=/tmp/jenkins-backup
   

2. Run the Jenkins WAR on a non-standard port (e.g., 9999):

   root@host:~# cd ~/jenkins-war
   root@host:~/jenkins-war# java -jar jenkins.war --httpPort=9999
   

3. Monitor startup output:

   Running from: /root/jenkins-war/jenkins.war
   Webroot: /tmp/jenkins-backup/war
   2025-02-07 07:21:04.103+0000 [id=1]  INFO  winstone.Logger#logInternal:
     Beginning extraction from war file
   2025-02-07 07:21:05.357+0000 [id=1]  INFO  hudson.WebAppMain#contextInitialized:
     Jenkins home directory: /tmp/jenkins-backup found at: EnvVars.masterEnvVars.get("JENKINS_HOME")
   2025-02-07 07:21:11.141+0000 [id=33] INFO  jenkins.lifecycle.Lifecycle#onReady:
     Jenkins is fully up and running
   

6. Validate in the Browser

Open your browser and navigate to:

http://<host>:9999

You should see the Jenkins login screen. After authentication, verify that:

• All your jobs are listed.
• Plugin manager shows installed plugins.
• Credentials, system configurations, and user accounts match production.

This successful validation confirms that your backup archive is complete and restorable.

Links and References

• Jenkins Backups and Restoration
• Jenkins CLI Documentation
• Jenkins War Runtime Options